The National Eye Institute Prospective ABCA4 Retinopathy Natural History Study: Fundus Guided Retinal Sensitivity Over 1 Year

Abstract

Purpose : To investigate retinal sensitivity measured with fundus guided perimetry prospectively over a year, in patients with ABCA4 retinopathy.

Methods : Fundus guided measurements of retinal sensitivity were recorded at baseline and then at 6 and 12 months from 48 patients with at least 1 mutation in ABCA4, and aged 12-63 yrs (median = 38 yrs). Right eye mesopic retinal sensitivity was measured to a 10-2 pattern. Left eye retinal sensitivity was measured with 2-color dark-adapted perimetry to a reverse L-shape pattern, centered on the fovea and extending 15^o nasally and 11^o superiorly.

Results : RIGHT EYE: Meaningful change in mesopic sensitivity for the 10-2 pattern was taken to be a loss of >=8dB in at least 5 points. Mesopic sensitivity measured to a 10-2 grid at baseline could be classified into 3 groups: Group 1 (n=29), no continuous breaks in outermost ring and >10 central points with reliable sensitivity (i.e. >=8dB). Group 2 (n=4): most of the 10-2 outer ring remained, but there were <5 central points with reliable sensitivity. Group 3 (n=12), <5 points across the entire 10-2 grid had a reliable sensitivity. Fifteen of the 20 Group 1 patients (75%) showed progression over 1 year. As Groups 2 and 3 had insufficient numbers of reliable points to follow, we trialed a modified extended pattern with 70 points extending 5 to 17 deg from the fovea along horizontal and vertical meridians. Retinal sensitivity could be measured along at least 1 axis, beginning 7 to 11 deg from the fovea in all Group 2 patients, and 8 of 12 (66%) Group 3 patients with a Goldman III (n=5) or V (n=3) stimulus. LEFT EYE: The length of the non-seeing area along a meridian was calculated as the distance (^o) from the fovea to a where a criterion threshold was reached. Repeatability coefficients (RCs) for the length of the non-seeing area were <2.5^o for the blue stimulus and <4^o deg for the red stimulus. Progression over 1 year was greater than variability determined from the RC in 6 of 28 patients (22%) recorded with the blue stimulus and 5 of 22 patients (22%) with the red stimulus.

Conclusions : With one year of follow-up, meaningful changes in both mesopic and scotopic retinal sensitivity could be documented in 15 and 6 ABCA4 patients respectively. The use of extended patterns combined with larger Goldman V stimuli enabled measurement of retinal sensitivity in advanced cases of ABCA4 retinopathy.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.